One other concern I've heard is that cut threads are an opportunity for stress risers and aren't recommended for that reason. I'd either use an AN490 end or, like Bob Barrows does on his designs, weld a nut on each end of a 4130 tube as in the next to last photo on this page:
<http://www.mykitlog.com/users/display_log.php?user=jonesronc&project=191&category=1716&log=84193&row=21> or http://tinyurl.com/cton4zl Patrick On Wed, December 19, 2012 12:40 pm, Oscar Zuniga wrote: > > >> At 06:20 AM 12/19/2012, you wrote: >> >How about 1/4" 4130 rod, threaded at each end to accept rod end >> >bearings?..aileron bellcranks. >> ++++++++++++++++++++++++++++++++++++++++++++++++++++ >> >> I suppose that would work but you would only have to thread the bolt >> on one end, not two. Whatever works for you. > > Recognize that 1/4" 4130 rod, even with deductions for material removed > during threading, will have a yield strength in tension of about 3000 lbs. > and an AN4 bolt will have roughly twice that strength. While these > choices of material are handy and conservative, they are not proportional > to the stress that they will see in service and milder materials may also > be used. If your ailerons go into flutter, I doubt that the rod end on > the bellcrank will be the weak link in the control system. > > However, I am not an aeronautical engineer and I did not sleep in a > Holiday Inn of any flavor last night. > > Oscar Zuniga > Medford, OR
